In conventional multi-chip modules where a number of semiconductor chips are integrated inside one package, signal transmission is carried out between semiconductor chips mounted in a multi-chip module through connections by means of wire bonding or a silicon interposer.
FIG. 23 is a diagram illustrating a conventional structure where semiconductor chips are mounted using bonding wires. Semiconductor chips 711 and 712 are mounted on a package substrate 81 in such a manner that the pads 721 and 722 provided on the respective semiconductor chips 711 and 712 are connected to the pads 82 provided on the package substrate 81 via bonding wires 731 and 732.
In the structure where semiconductor chips are mounted using bonding wires, the mounting area and the consumed energy can be reduced, and therefore, the structure is often used for mobile devices. An issue in this mounting system is a low data transfer rate. That is to say, there is a problem such that the data transfer rate is limited by the number of bonding wires that can be connected.
Meanwhile, SiP technologies using a silicon interposer (see Non-Patent Document 1 and Non-Patent Document 2) are characterized in that the data transfer between chips can be carried out at a high rate and with low power. FIG. 24 is a diagram illustrating a conventional structure where semiconductor chips are mounted using a silicon interposer. Semiconductor chips 911 and 912 are flip-chip bonded on a package substrate 98 via a silicon interposer 93. The silicon interposer 93 is provided with pads 94, vias (TSVs) 95, wires 96 and C4 (controlled collapse chip connection) bumps 97.
The semiconductor chip 911 and the semiconductor chip 912 are connected to each other via the micro-bumps 921 and 922, pads 94, vias (TSVs) 95 and wires 96. In addition, the semiconductor chip 911 and the semiconductor chip 912 are connected to the pads 99 provided on the package substrate 98 via the pads 94, the vias (TSVs) 95 and C4 bumps 97.
In the case of SiP technologies, however, a large silicon interposer, fine micro-bumps and TSVs (through-silicon vias) are required, and an issue includes a high mounting cost.
In order to solve such a problem caused by bonding wires and a silicon interposer, methods for carrying out signal transmission in a noncontact manner using capacitances and coils have been proposed in recent years. For example, the present inventor has proposed communication between chips layered and mounted on a semiconductor chip through inductive coupling via coils formed of wires on the chip (see Patent Document 1 and Non-Patent Document 3).
In these proposals, noncontact signal transmission is made possible by allowing a signal current on which data is superposed to flow through a transmission and reception coil formed on a first semiconductor chip so that a power that has been induced in a transmission and reception coil formed on a second semiconductor chip placed above or below the first semiconductor chip can be detected.
These technologies can be used to make data transfer between a number of IC chips possible through wireless communication. As a result, neither wires for data communication nor a large interposer are necessary, and therefore, the number of wires for wire bonding can be reduced, and the number of chips that are layered on top of each other can be increased.